U.S. patent application number 12/604906 was filed with the patent office on 2010-05-13 for image input-output device.
This patent application is currently assigned to SEMICONDUCTOR ENERGY LABORATORY CO., LTD.. Invention is credited to Jun KOYAMA, Shunpei YAMAZAKI.
Application Number | 20100117991 12/604906 |
Document ID | / |
Family ID | 42164777 |
Filed Date | 2010-05-13 |
United States Patent
Application |
20100117991 |
Kind Code |
A1 |
KOYAMA; Jun ; et
al. |
May 13, 2010 |
IMAGE INPUT-OUTPUT DEVICE
Abstract
An image input-output device includes a pixel which displays an
image and reads an image. The pixel includes a photodetector
element, a color layer, and a display element. The color layer is
provided over the photodetector element and the display element is
provided over the color layer, so that the distance between the
photodetector element and the color layer is reduced. Accordingly,
light is likely to enter the predetermined photodetector element
through the predetermined color layer, and thus, even a color
object can be read correctly.
Inventors: |
KOYAMA; Jun; (Sagamihara,
JP) ; YAMAZAKI; Shunpei; ( Tokyo, JP) |
Correspondence
Address: |
NIXON PEABODY, LLP
401 9TH STREET, NW, SUITE 900
WASHINGTON
DC
20004-2128
US
|
Assignee: |
SEMICONDUCTOR ENERGY LABORATORY
CO., LTD.
Atsugi-shi
JP
|
Family ID: |
42164777 |
Appl. No.: |
12/604906 |
Filed: |
October 23, 2009 |
Current U.S.
Class: |
345/175 ;
250/214.1; 250/226; 349/12 |
Current CPC
Class: |
H01L 27/326 20130101;
H01L 27/14678 20130101; H01L 27/322 20130101; H01L 31/02162
20130101; G02F 1/133514 20130101; G02F 1/136222 20210101; H01L
27/3213 20130101; H01L 2227/323 20130101; G06F 3/0412 20130101;
G02F 1/13312 20210101; G02F 1/13338 20130101; G06F 3/042 20130101;
H01L 27/3234 20130101 |
Class at
Publication: |
345/175 ;
250/226; 250/214.1; 349/12 |
International
Class: |
G06F 3/042 20060101
G06F003/042; H01L 31/0232 20060101 H01L031/0232; H01L 27/144
20060101 H01L027/144; H01L 31/101 20060101 H01L031/101; G02F 1/1335
20060101 G02F001/1335 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 7, 2008 |
JP |
2008-286043 |
Claims
1. An image input-output device comprising a pixel configured to
display an image and configured to read an image, wherein the pixel
includes a photodetector element, a color layer provided over the
photodetector element, and a display element provided over the
color layer.
2. The image input-output device according to claim 1, wherein the
photodetector element includes: a first semiconductor layer having
one of p-type conductivity and n-type conductivity; a second
semiconductor layer which is provided over the first semiconductor
layer and has a higher resistance than the first semiconductor
layer; and a third semiconductor layer which is provided over the
second semiconductor layer, and has the other of p-type
conductivity and n-type conductivity and a lower resistance than
the second semiconductor layer.
3. The image input-output device according to claim 1, wherein the
photodetector element includes a semiconductor layer including a
first semiconductor region having one of p-type conductivity and
n-type conductivity; a second semiconductor region having a higher
resistance than the first semiconductor region; and a third
semiconductor region having the other of p-type conductivity and
n-type conductivity and a lower resistance than the second
semiconductor region.
4. The image input-output device according to claim 1, wherein the
display element is a liquid crystal element.
5. The image input-output device according to claim 1, wherein the
photodetector element generates a current in accordance with the
illuminance of incident light through the color layer.
6. The image input-output device according to claim 1, wherein the
color layer is a color layer of at least any of red, green, and
blue.
7. The image input-output device according to claim 1, wherein the
image input-output device has a function of inputting and
outputting text.
8. The image input-output device according to claim 1, wherein the
image input-output device is incorporated into an electronic device
selected from the group consisting of a personal digital assistant,
an information guide terminal, a laptop personal computer, a
portable game machine, a stationary information terminal, and a
display.
9. An image input-output device comprising: a substrate; and a
pixel which is provided over the substrate, and configured to
display an image and configured to read an image, wherein the pixel
includes: a first transistor and a second transistor; a
photodetector element having an anode and a cathode, one of which
is electrically connected to a gate electrode of the second
transistor; a first protective film provided over the first
transistor, the second transistor, and the photodetector element; a
color layer provided over the first protective film; a second
protective film provided over the color layer; and a liquid crystal
element provided over the second protective film, and wherein the
liquid crystal element includes: a first electrode electrically
connected to a source electrode or a drain electrode of the first
transistor through an opening portion provided in the first
protective film, the color layer, and the second protective film; a
second electrode; and a liquid crystal layer to which a voltage is
configured to be applied by the first electrode and the second
electrode.
10. The image input-output device according to claim 9, wherein the
photodetector element includes: a first semiconductor layer having
one of p-type conductivity and n-type conductivity; a second
semiconductor layer which is provided over the first semiconductor
layer and has a higher resistance than the first semiconductor
layer; and a third semiconductor layer which is provided over the
second semiconductor layer, and has the other of p-type
conductivity and n-type conductivity and a lower resistance than
the second semiconductor layer.
11. The image input-output device according to claim 9, wherein the
photodetector element includes a semiconductor layer including a
first semiconductor region having one of p-type conductivity and
n-type conductivity; a second semiconductor region having a higher
resistance than the first semiconductor region; and a third
semiconductor region having the other of p-type conductivity and
n-type conductivity and a lower resistance than the second
semiconductor region.
12. The image input-output device according to claim 9, wherein the
photodetector element generates a current in accordance with the
illuminance of incident light through the color layer.
13. The image input-output device according to claim 9, wherein the
color layer is a color layer of at least any of red, green, and
blue.
14. The image input-output device according to claim 9, wherein the
image input-output device has a function of inputting and
outputting text.
15. The image input-output device according to claim 9, wherein the
image input-output device is incorporated into an electronic device
selected from the group consisting of a personal digital assistant,
an information guide terminal, a laptop personal computer, a
portable game machine, a stationary information terminal, and a
display.
16. The image input-output device according to claim 9, wherein the
substrate is a flexible substrate.
17. The image input-output device according to claim 9, wherein the
photodetector element overlaps with the second transistor.
18. The image input-output device according to claim 9, wherein the
first electrode overlaps with the photodetector element.
19. An image input-output device comprising: a substrate; and a
pixel which is provided over the substrate, and configured to
display an image and configured to read an image, wherein the pixel
includes: a first transistor and a second transistor; a
photodetector element having an anode and a cathode, one of which
is electrically connected to a gate electrode of the second
transistor; a first protective film provided over the first
transistor, the second transistor, and the photodetector element; a
light blocking layer selectively provided over the first protective
film; a color layer provided over part of the first protective
film, where the light blocking layer is not provided; a second
protective film provided over the light blocking layer and the
color layer; and a liquid crystal element provided over the second
protective film, and wherein the liquid crystal element includes: a
first electrode electrically connected to a source electrode or a
drain electrode of the first transistor through an opening portion
provided in the first protective film, the color layer, and the
second protective film; a second electrode; and a liquid crystal
layer to which a voltage is applied by the first electrode and the
second electrode.
20. The image input-output device according to claim 19, wherein
the photodetector element includes: a first semiconductor layer
having one of p-type conductivity and n-type conductivity; a second
semiconductor layer which is provided over the first semiconductor
layer and has a higher resistance than the first semiconductor
layer; and a third semiconductor layer which is provided over the
second semiconductor layer, and has the other of p-type
conductivity and n-type conductivity and a lower resistance than
the second semiconductor layer.
21. The image input-output device according to claim 19, wherein
the photodetector element includes a semiconductor layer including
a first semiconductor region having one of p-type conductivity and
n-type conductivity; a second semiconductor region having a higher
resistance than the first semiconductor region; and a third
semiconductor region having the other of p-type conductivity and
n-type conductivity and a lower resistance than the second
semiconductor region.
22. The image input-output device according to claim 19, wherein
the photodetector element generates a current in accordance with
the illuminance of incident light through the color layer.
23. The image input-output device according to claim 19, wherein
the color layer is a color layer of at least any of red, green, and
blue.
24. The image input-output device according to claim 19, wherein
the image input-output device has a function of inputting and
outputting text.
25. The image input-output device according to claim 19, wherein
the image input-output device is incorporated into an electronic
device selected from the group consisting of a personal digital
assistant, an information guide terminal, a laptop personal
computer, a portable game machine, a stationary information
terminal, and a display.
26. The image input-output device according to claim 19, wherein
the substrate is a flexible substrate.
27. The image input-output device according to claim 19, wherein
the photodetector element overlaps with the second transistor.
28. The image input-output device according to claim 19, wherein
the first electrode overlaps with the photodetector element.
29. The image input-output device according to claim 19, wherein
the light blocking layer overlaps with the first transistor.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an image input-output
device having functions of inputting and outputting images.
[0003] 2. Description of the Related Art
[0004] In recent years, a device having a display (output) function
and a read (input) function (hereinafter referred to as an image
input-output device) is known as a multifunctional device obtained
by adding another function to a display device such as a liquid
crystal display device.
[0005] An image input-output device includes a display element and
a photodetector element in a pixel portion, performs display
operation using the display element, and can read an object to be
read (e.g., a finger, a pen, or a document) using the photodetector
element. With this structure, the image input-output device can
have, for example, a function of a touch panel, such as functions
of detecting position and inputting and outputting text, a
fingerprint identification function, and functions of performing
read operation like a scanner and displaying a read image on a
display portion. Moreover, when a color filter (also referred to as
a color layer), for example, is used for read operation, an object
is read in color and can be displayed in full color (e.g., see
Patent Document 1).
[0006] [Reference]
[0007] Patent Document 1: Japanese Published Patent Application No.
2007-033789
SUMMARY OF THE INVENTION
[0008] A conventional image input-output device disclosed in Patent
Document 1 includes a display element and a light receiving element
(also referred to as a photodetector element) in a pixel. One of
substrates (a TFT substrate) is provided with the display element
and the light receiving element. The other substrate (a counter
electrode substrate) is provided with a color layer (a color
filter). The two substrates are attached to each other. When one
substrate is considered as the bottom, the color layer is placed
above the display element. With such a structure, the display
element is placed between the color layer and the light receiving
element with a certain distance between the color layer and the
light receiving element; accordingly, it is highly possible that
incident light at the time of reading enters the light receiving
element without passing through the color layer. When incident
light enters the light receiving element without passing through
the color layer, the color of an object cannot be read correctly.
Accordingly, a conventional image input-output device has a problem
of low reading accuracy.
[0009] In view of the foregoing problem, an object of one
embodiment of the present invention is to improve the accuracy of
reading images, and particularly the accuracy of reading images in
color.
[0010] One embodiment of the invention disclosed in this
specification is an image input-output device including a pixel
which displays an image and reads an image. The pixel includes a
photodetector element, a color layer, and a display element. The
color layer is provided over the photodetector element and the
display element is provided over the color layer, so that the
distance between the photodetector element and the color layer is
reduced.
[0011] A structure of an image input-output device, which is one
embodiment of the invention disclosed in this specification, is as
follows. The image input-output device includes a pixel which
displays an image and reads an image. The pixel includes a
photodetector element, a color layer provided over the
photodetector element, and a display element provided over the
color layer.
[0012] Another structure of an image input-output device is as
follows. The image input-output device includes a pixel which
displays an image and reads an image. The pixel includes a first
transistor and a second transistor; a photodetector element having
an anode and a cathode, one of which is electrically connected to a
gate electrode of the second transistor; a first protective film
provided over the first transistor, the second transistor, and the
photodetector element; a color layer provided over the first
protective film; a second protective film provided over the color
layer; and a liquid crystal element provided over the second
protective film. The liquid crystal element includes a first
electrode electrically connected to a source electrode or a drain
electrode of the first transistor through an opening portion
provided in the first protective film, the color layer, and the
second protective film; a second electrode; and a liquid crystal
layer to which a voltage is applied by the first electrode and the
second electrode.
[0013] Another structure of an image input-output device is as
follows. The image input-output device includes a pixel which
displays an image and reads an image. The pixel includes a first
transistor and a second transistor; a photodetector element having
an anode and a cathode, one of which is electrically connected to a
gate electrode of the second transistor; a first protective film
provided over the first transistor, the second transistor, and the
photodetector element; a light blocking layer provided over the
first transistor or the second transistor with the first protective
film therebetween; a color layer provided over part of the first
protective film, where the light blocking layer is not provided; a
second protective film provided over the light blocking layer and
the color layer; and a liquid crystal element provided over the
second protective film. The liquid crystal element includes a first
electrode electrically connected to a source electrode or a drain
electrode of the first transistor through an opening portion
provided in the first protective film, the color layer, and the
second protective film; a second electrode; and a liquid crystal
layer to which a voltage is applied by the first electrode and the
second electrode.
[0014] The photodetector element can include a first semiconductor
layer having one of p-type conductivity and n-type conductivity; a
second semiconductor layer which is provided over the first
semiconductor layer and has a higher resistance than the first
semiconductor layer; and a third semiconductor layer which is
provided over the second semiconductor layer, and has the other of
p-type conductivity and n-type conductivity and a lower resistance
than the second semiconductor layer.
[0015] The photodetector element can include a semiconductor layer
including a first semiconductor region having one of p-type
conductivity and n-type conductivity; a second semiconductor region
having a higher resistance than the first semiconductor region; and
a third semiconductor region having the other of p-type
conductivity and n-type conductivity and a lower resistance than
the second semiconductor region.
[0016] Note that in this specification, terms with ordinal numbers,
such as "first" and "second", are used in order to avoid confusion
among components, and the terms do not limit the components
numerically.
[0017] When the distance between the photodetector element and the
color layer is reduced, light is likely to enter the photodetector
element through the color layer. Accordingly, even a color object
can be read correctly, and the reading accuracy can be
improved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] In the accompanying drawings:
[0019] FIG. 1 is a cross-sectional view illustrating an example of
a structure of a pixel in an image input-output device in
Embodiment 1;
[0020] FIG. 2 is a circuit diagram illustrating an example of a
circuit configuration of a pixel portion in an image input-output
device in Embodiment 2;
[0021] FIGS. 3A and 3B are block diagrams each illustrating an
example of a structure of a pixel portion in an image input-output
device in Embodiment 2;
[0022] FIG. 4 is a circuit diagram illustrating an example of a
structure of a pixel portion in an image input-output device in
Embodiment 2;
[0023] FIG. 5 is a cross-sectional view illustrating an example of
a structure of a pixel portion in an image input-output device in
Embodiment 2;
[0024] FIG. 6 is a cross-sectional view illustrating an example of
a structure of a pixel in an image input-output device in
Embodiment 2;
[0025] FIG. 7 is a cross-sectional view illustrating an example of
a structure of an image input-output device in Embodiment 2 in the
case where a light blocking layer is provided in the image
input-output device;
[0026] FIGS. 8A and 8B each illustrate a function of an image
input-output device in Embodiment 2;
[0027] FIG. 9 illustrates a function of an image input-output
device in Embodiment 2;
[0028] FIGS. 10A to 10C are cross-sectional views illustrating an
example of a method for manufacturing a pixel in an image
input-output device in Embodiment 3;
[0029] FIGS. 11A to 11C are cross-sectional views illustrating an
example of a method for manufacturing a pixel in an image
input-output device in Embodiment 3;
[0030] FIGS. 12A and 12B are cross-sectional views illustrating an
example of a method for manufacturing a pixel in an image
input-output device in Embodiment 3;
[0031] FIGS. 13A and 13B are cross-sectional views illustrating an
example of a method for manufacturing a pixel in an image
input-output device in Embodiment 3;
[0032] FIGS. 14A and 14B are cross-sectional views illustrating an
example of a method for manufacturing a pixel in an image
input-output device in Embodiment 3;
[0033] FIGS. 15A and 15B are cross-sectional views illustrating an
example of a method for manufacturing a pixel in an image
input-output device in Embodiment 3;
[0034] FIG. 16 is a cross-sectional view illustrating an example of
a method for manufacturing a pixel in an image input-output device
in Embodiment 3;
[0035] FIGS. 17A to 17C are cross-sectional views illustrating an
example of a method for manufacturing a color layer and a light
blocking layer in an image input-output device in Embodiment 4;
[0036] FIG. 18 is a block diagram illustrating an example of a
structure of an image input-output device in Embodiment 5; and
[0037] FIGS. 19A to 19F each illustrate an example of a structure
of an electronic device including an image input-output device in
Embodiment 6 in a display portion.
DETAILED DESCRIPTION OF THE INVENTION
[0038] Embodiments of the invention disclosed in this specification
will be described below with reference to the accompanying
drawings. Note that the invention disclosed in this specification
is not limited to the following description, and it is easily
understood by those skilled in the art that modes and details can
be variously changed without departing from the spirit and the
scope of the invention. Therefore, the invention disclosed in this
specification is not construed as being limited to the description
of the following embodiments.
Embodiment 1
[0039] In this embodiment, an image input-output device, which is
one embodiment of the invention disclosed in this specification,
will be described.
[0040] An image input-output device in this embodiment includes a
pixel which displays an image and reads an image, and it is
possible to perform image display (also referred to as output
operation) and image reading (also referred to as input operation)
in each pixel. A pixel structure will be described with reference
to FIG. 1. FIG. 1 is a cross-sectional view illustrating an example
of a structure of a pixel in the image input-output device in this
embodiment.
[0041] The pixel illustrated in FIG. 1 includes a photodetector
element 102 provided over a substrate 101, a color layer 103
provided over the photodetector element 102, and a display element
104 provided over the color layer 103.
[0042] Note that when it is explicitly described that B is provided
(formed) on or over A, it does not necessarily mean that B is
provided (formed) in direct contact with A. The description
includes the case where A and B are not in direct contact with each
other, that is, the case where another object is placed between A
and B. Here, each of A and B corresponds to an object (e.g., an
element, a wiring, an electrode, or a layer).
[0043] Accordingly, for example, when it is explicitly described
that a layer B is provided (formed) on or over a layer A, the
description includes both the case where the layer B is provided
(formed) in direct contact with the layer A, and the case where
another layer (e.g., a layer C or a layer D) is provided (formed)
in direct contact with the layer A and the layer B is provided
(formed) in direct contact with the layer C or the layer D. Note
that another layer (e.g., the layer C or the layer D) may be a
single layer or a plurality of layers.
[0044] As the substrate 101, a glass substrate, a quartz substrate,
or a flexible substrate can be used, for example. The flexible
substrate refers to a substrate which can be bent (is flexible). An
example of the flexible substrate is a plastic substrate formed
using polycarbonate, polyarylate, polyethersulfone, or the like.
Alternatively, as the substrate 101, an attachment film (formed
using polypropylene, polyester, vinyl, polyvinyl fluoride, vinyl
chloride, or the like), paper of a fibrous material, a base
material film (polyester, polyamide, an inorganic vapor deposition
film, paper, or the like), or the like can be used.
[0045] The photodetector element 102 has a function of generating
current in accordance with the illuminance of incident light, and
is an element for reading an image. The photodetector element 102
can be formed using a photodiode or a phototransistor, for
example.
[0046] The color layer 103 is also referred to as a color filter,
and expresses a color by extracting light with a predetermined
wavelength from incident light. A color layer of at least any of
red (R), green (G), and blue (B) can be used as the color layer
103, Moreover, the color layer 103 can be formed by a
photolithography method or an inkjet method, for example.
[0047] Further, in the image input-output device in this
embodiment, the color layer 103 can also function as a
planarization film. As illustrated in FIG. 1, over the substrate
101, difference in height occurs between a region including the
photodetector element 102 and other regions. However, the provision
of the color layer 103 can reduce, preferably eliminate, the
difference in height.
[0048] Note that in the image input-output device in this
embodiment, a protective film which prevents diffusion of
impurities from the color layer 103 can be provided. The provision
of the protective film can prevent a pigment or a dye in the color
layer 103, for example, from diffusing into another layer.
[0049] The display element 104 performs display operation and can
be formed using a liquid crystal element or an EL element, for
example.
[0050] Next, operation of the image input-output device in this
embodiment will be described using the image input-output device
illustrated in FIG. 1 as an example.
[0051] The operation of the image input-output device in this
embodiment is mainly classified into display operation and read
operation. Each operation will be described below.
[0052] The display operation is as follows. Image data is input to
a pixel, a voltage is applied to the display element 104 in the
pixel based on the input image data, and the display element 104
performs the display operation in accordance with the applied
voltage.
[0053] The read operation is as follows. A current is generated by
the photodetector element 102 in accordance with the illuminance of
incident light, and the generated current is used as image data, so
that the read operation is performed. Note that since light enters
the photodetector element 102 through the color layer 103, data of
a color image is obtained by reading an object.
[0054] As described above, the image input-output device in this
embodiment has a structure where the color layer is provided over
the photodetector element, and the display element is provided over
the color layer. This structure can reduce the distance between the
photodetector element and the color layer, and can prevent light
from entering, for example, a photodetector element on which light
passing through a color layer of a predetermined color is to enter,
through a color filter of a color other than the predetermined
color. Accordingly, even a color object can be read correctly, and
the reading accuracy can be improved.
Embodiment 2
[0055] In this embodiment, an image input-output device using a
liquid crystal element as a display element will be described as
one embodiment of the invention disclosed in this
specification.
[0056] First, a circuit configuration of a pixel in an image
input-output device in this embodiment will be described with
reference to FIG. 2. FIG. 2 is a circuit diagram illustrating an
example of a circuit configuration of a pixel in the image
input-output device in this embodiment.
[0057] As illustrated in FIG. 2, the pixel in the image
input-output device in this embodiment is divided into a display
circuit 302 and a photodetector circuit 303. The display circuit
302 includes a transistor 321, a liquid crystal element 322, and a
capacitor 323. The photodetector circuit 303 includes a transistor
331 and a photodetector element 332.
[0058] Note that in this specification, a transistor has at least
three terminals of a gate, a source, and a drain.
[0059] The gate is the entire gate electrode and gate wiring or
part thereof. The gate wiring is a wiring for electrically
connecting a gate electrode of at least one transistor to another
electrode or another wiring, and includes a scan line in a display
device in its category, for example.
[0060] The source is the entire source region, source electrode,
and source wiring or part thereof. The source region indicates a
region in a semiconductor layer, which has a resistivity lower than
a given value and functions as the source of the transistor. The
source electrode indicates part of a conductive layer, which is
connected to the source region. The source wiring is a wiring for
electrically connecting a source electrode of at least one
transistor to another electrode or another wiring. For example, in
the case where a signal line in a display device is electrically
connected to a source electrode, the source wiring includes the
signal line in its category.
[0061] The drain is the entire drain region, drain electrode, and
drain wiring or part thereof. The drain region indicates a region
in a semiconductor layer, which has a resistivity lower than a
given value and functions as the drain of the transistor. The drain
electrode indicates part of a conductive layer, which is connected
to the drain region. The drain wiring is a wiring for electrically
connecting a drain electrode of at least one transistor to another
electrode or another wiring. For example, in the case where a
signal line in a display device is electrically connected to a
drain electrode, the drain wiring includes the signal line in its
category.
[0062] In addition, in this specification, a source and a drain of
a transistor change depending on the structure, the operating
conditions, or the like of the transistor; therefore, it is
difficult to define which terminal is the source and which terminal
is the drain. Accordingly, in this specification, one terminal
which is freely selected from the source and the drain is referred
to as one of the source and the drain, whereas the other terminal
is referred to as the other of the source and the drain.
[0063] A gate of the transistor 321 is electrically connected to a
scan line 304, and one of a source and a drain of the transistor
321 is electrically connected to a signal line 305.
[0064] The liquid crystal element 322 has a first terminal and a
second terminal. The first terminal is electrically connected to
the other of the source and the drain of the transistor 321. A
ground potential or a potential with a given value is supplied to
the second terminal. The liquid crystal element 322 includes a
first electrode which serves as part or all of the first terminal,
a second electrode which serves as part or all of the second
terminal, and a layer including liquid crystal molecules whose
transmittance is changed by applying voltage between the first
electrode and the second electrode (such a layer is referred to as
a liquid crystal layer).
[0065] Note that the following liquid crystals can be used for the
liquid crystal element: a nematic liquid crystal, a cholesteric
liquid crystal, a smectic liquid crystal, a discotic liquid
crystal, a thermotropic liquid crystal, a lyotropic liquid crystal,
a low molecular liquid crystal, a high molecular liquid crystal, a
polymer dispersed liquid crystal (PDLC), a ferroelectric liquid
crystal, an anti-ferroelectric liquid crystal, a main chain type
liquid crystal, a side chain type polymer liquid crystal, a plasma
addressed liquid crystal (PALC), and a banana-shaped liquid
crystal. Moreover, the following driving methods of a liquid
crystal can be used, for example: a TN (twisted nematic) mode, an
STN (super twisted nematic) mode, an IPS (in-plane-switching) mode,
an FFS (fringe field switching) mode, an MVA (multi-domain vertical
alignment) mode, a PVA (patterned vertical alignment) mode, an ASV
(advanced super view) mode, an ASM (axially symmetric aligned
microcell) mode, an OCB (optically compensated birefringence) mode,
an ECB (electrically controlled birefringence) mode, an FLC
(ferroelectric liquid crystal) mode, an AFLC (anti-ferroelectric
liquid crystal) mode, a PDLC (polymer dispersed liquid crystal)
mode, a guest-host mode, and a blue phase mode.
[0066] The capacitor 323 functions as a storage capacitor, and has
a first terminal and a second terminal. The first terminal is
electrically connected to the other of the source and the drain of
the transistor 321. The ground potential or a potential with a
given value is supplied to the second terminal. The capacitor 323
includes a first electrode which serves as part or all of the first
terminal, a second electrode which serves as part or all of the
second terminal, and a dielectric layer. Note that the capacitor
323 is not necessarily provided.
[0067] One of a source and a drain of the transistor 331 is
electrically connected to the signal line 305, and the other of the
source and the drain of the transistor 331 is electrically
connected to the scan line 304.
[0068] The photodetector element 332 has an anode and a cathode.
The anode is electrically connected to a gate of the transistor
331. The cathode is electrically connected to a potential control
line 306. As an example, a PIN diode is used as the photodetector
element 332 in this embodiment. The PIN diode includes a layer or a
region having p-type conductivity, which serves as the anode; a
layer or a region having n-type conductivity, which serves as the
cathode; and a high resistance region which is provided between the
anode and the cathode, and has a higher resistance than the anode
and the cathode.
[0069] When a pixel portion is constituted by a plurality of
pixels, the pixel portion of the image input-output device in this
embodiment can have a structure illustrated in FIGS. 3A and 3B.
FIGS. 3A and 3B are block diagrams each illustrating an example of
a structure of a pixel portion in the image input-output device in
this embodiment.
[0070] A pixel portion 301 of an image input-output device 300
illustrated in FIG. 3A has a structure where one photodetector
circuit 303 is provided for one display circuit 302 (such a
structure is also referred to as a first structure). For example,
when full color display is performed with the first structure by
using a plurality of colors such as RGB, one pixel is constituted
by three display circuits and three photodetector circuits, and
read operation for the respective colors can be performed by the
photodetector circuits 303. Accordingly. the read operation can be
performed with more accuracy.
[0071] Further, the pixel portion 301 of the image input-output
device 300 illustrated in FIG. 313 has a structure where one
photodetector circuit 303 is provided for a plurality of display
circuits 302 (three display circuits 302 in FIG. 3B) (such a
structure is also referred to as a second structure). For example,
when full color display is performed with the second structure by
using a plurality of colors such as RGB, one pixel is constituted
by three display circuits and one photodetector circuit, and read
operation for a plurality of colors can be performed by one
photodetector circuit 303. Thus, the circuit area can be
reduced.
[0072] Next, operation of the pixel illustrated in FIG. 2 will be
described.
[0073] The operation of the pixel in FIG. 2 is classified into two
periods of a display (output) period and a read (input) period. The
operation in each period will be described below.
[0074] In the display period, the transistor 321 is turned on by a
signal input from the scan line 304.
[0075] At this time, a potential corresponding to a data signal is
supplied from the signal line 305 to the first terminal of the
liquid crystal element 322, so that a potential of the first
terminal of the liquid crystal element 322 becomes a potential of
the data signal (also referred to as Vdata), and the transmittance
of the liquid crystal element 322 is set in accordance with voltage
applied between the first terminal and the second terminal. After
data writing, the transistor 321 is turned off by a scan signal
input from the scan line 304, the transmittance of the liquid
crystal element 322 is maintained during the display period, and
the pixel enters into a display state. The above operation is
sequentially performed every scan line 304, so that the data
writing and display are performed in all the pixels.
[0076] In the read period, the photodetector circuit 303 by which
the illuminance of incident light is read as data is selected. In
the selected photodetector circuit 303, a potential higher than a
given potential is supplied from the potential control line 306 to
the cathode of the photodetector element 332, and the gate of the
transistor 331 is supplied with a potential obtained by adding a
voltage applied between the anode and the cathode of the
photodetector element 332 to a potential of the potential control
line 306. At this time, a current corresponding to the illuminance
of incident light is generated by the photodetector element 332, so
that a voltage corresponding to the illuminance of light entering
the photodetector element 332 is applied between the anode and the
cathode of the photodetector element 332. Moreover, the signal line
305 is precharged to a fixed potential.
[0077] Further, when the transistor 331 is turned on, electric
charge is discharged from the signal line 305. At this time, a
potential of the scan line 304 is set lower than the given
potential in advance so that a current flows from the signal line
305 to the scan line 304. The read operation can be performed by
reading the potential of the signal line 305 as data.
[0078] Note that the pixel of the image input-output device in this
embodiment is not limited to having the circuit configuration
illustrated in FIG. 2, and can have the following structures, for
example: a structure A where a selection line and a selection
switch are added to the circuit configuration in FIG. 2, a
structure B where a reset control line and a reset switch are added
to the circuit configuration in FIG. 2, and a structure C obtained
by combining the structure A and the structure B. Another structure
of the pixel is described with reference to FIG. 4. FIG. 4 is a
circuit diagram illustrating an example of a structure of the pixel
in the image input-output device in this embodiment. In FIG. 4, the
structure C is illustrated as an example.
[0079] Like the pixel illustrated in FIG. 2, the pixel illustrated
in FIG. 4 is divided into the display circuit 302 and the
photodetector circuit 303. The display circuit 302 has the same
structure as the display circuit 302 in FIG. 2, and includes the
transistor 321, the liquid crystal element 322, and the capacitor
323. Note that in the pixel in FIG, 4, the description of the pixel
in FIG. 2 is employed as appropriate for the same portions as the
pixel in FIG. 2.
[0080] The photodetector circuit 303 includes a transistor 333, a
transistor 334, a transistor 335, and the photodetector element
332.
[0081] The transistor 333 functions as a selection switch. A gate
of the transistor 333 is electrically connected to a scan line 309,
and one of a source and a drain of the transistor 333 is
electrically connected to the signal line 305.
[0082] The transistor 334 functions as an amplifier element. One of
a source and a drain of the transistor 334 is electrically
connected to a power supply line 308, and the other of the source
and the drain of the transistor 334 is electrically connected to
the other of the source and the drain of the transistor 333.
[0083] The transistor 335 functions as a reset switch. A gate of
the transistor 335 is electrically connected to a reset control
line 307, one of a source and a drain of the transistor 335 is
electrically connected to the power supply line 308, and the other
of the source and the drain of the transistor 335 is electrically
connected to a gate of the transistor 334.
[0084] The ground potential or a constant potential with a given
value is supplied to the anode of the photodetector element 332.
The cathode of the photodetector element 332 is electrically
connected to the other of the source and the drain of the
transistor 335.
[0085] Note that as each of the transistors 333 to 335, a
transistor with a structure which can be applied to the transistor
331 illustrated in FIG. 2 can be used, for example.
[0086] In the pixel illustrated in FIG. 4, the photodetector
circuit 303 is constituted by a plurality of transistors. By
forming the photodetector circuit 303 using a plurality of
transistors, stable read operation can be performed.
[0087] Next, operation of the pixel illustrated in FIG. 4 will be
described.
[0088] In the display period, the transistor 321 is turned on by a
signal input from the scan line 304.
[0089] At this time, a potential corresponding to a data signal is
supplied from the signal line 305 to the first terminal of the
liquid crystal element 322, so that a potential of the first
terminal of the liquid crystal element 322 becomes Vdata, and the
transmittance of the liquid crystal element 322 is set in
accordance with voltage applied between the first terminal and the
second terminal. After data writing, the transistor 321 is turned
off by a scan signal input from the scan line 304, the
transmittance of the liquid crystal element 322 is maintained
during the display period, and the pixel enters into a display
state. The above operation is sequentially performed every scan
line 304, so that the data writing and display are performed in all
the pixels.
[0090] In the read period, first, the transistor 335 is turned on
by a reset signal input from the reset control line 307. At this
time, a potential at a node of the transistors 334 and 335 and the
photodetector element 332 is equal to the potential of the power
supply line 308, and the node enters into a reset state.
[0091] After the reset of the node, the transistor 335 is turned
off. At this time, a current corresponding to the illuminance of
incident light is generated by the photodetector element 332, and a
potential of the gate of the transistor 334 is reduced by the
generated current. Moreover, the transistor 333 is turned on by a
signal input from the scan line 309. Accordingly, a potential of
the cathode of the photodetector element 332 is supplied to the
signal line 305 through the transistors 333 and 334. The read
operation is performed using the potential of the signal line 305
as image data.
[0092] Next, a structure of the pixel in the image input-output
device in this embodiment will be described with reference to FIG.
5. FIG. 5 is a cross-sectional view illustrating an example of a
structure of the pixel in the image input-output device in this
embodiment.
[0093] A pixel illustrated in FIG. 5 includes a substrate 501, a
base film 502, an element formation layer 503, an interlayer film
512, an electrode 5131, the photodetector element 332, a protective
film 517, a color layer 518, a protective film 519, the liquid
crystal element 322, an electrode 5202, and a substrate 524.
[0094] In the pixel in FIG. 5, the base film 502 is provided over
the substrate 501. The element formation layer 503 is provided over
the base film 502. The interlayer film 512 is provided over the
element formation layer 503. The electrode 5131, the photodetector
element 332, and an electrode 5133 are provided over the interlayer
film 512. The protective film 517 is provided over the electrode
5131 and the photodetector element 332. The color layer 518 is
provided over the protective film 517. The protective film 519 is
provided over the color layer 518.
[0095] As the substrate 501, any of the substrates which can be
used as the substrate 101 illustrated in FIG. 1 in Embodiment 1 can
be used.
[0096] As the base film 502, a silicon oxide film, a silicon
nitride film, or a silicon oxide film containing nitrogen can be
used, for example. Alternatively, the base film 502 can be provided
by stacking the above silicon films. Note that although the base
film 502 is not necessarily provided, the provision of the base
film 502 can prevent impurities such as alkali metal from the
substrate 501 from diffusing into the layers formed over the base
film 502, for example. Further, when the base film 502 is provided,
a silicon substrate, a metal substrate, a stainless steel
substrate, or the like can also be used as the substrate 501.
[0097] The element formation layer 503 includes at least the
transistor 321, the capacitor 323, and the transistor 331. The
structure of the element formation layer 503 will be described
below.
[0098] The element formation layer 503 includes semiconductor
layers 5031, 5032, and 5033; an insulating film 506; conductive
layers 5071, 5072, and 5073; conductive layers 5081, 5082, and
5083; interlayer films 509 and 510; a pair of electrodes 5111; a
pair of electrodes 5112; and a pair of electrodes 5113.
[0099] The semiconductor layers 5031 to 5033 are provided over the
base film 502. The insulating film 506 is provided over the
semiconductor layers 5031 to 5033. The conductive layer 5071 is
provided over part of the insulating film 506 formed over the
semiconductor layer 5031. The conductive layer 5072 is provided
over part of the insulating film 506 formed over the semiconductor
layer 5032. The conductive layer 5073 is provided over part of the
insulating film 506 formed over the semiconductor layer 5033. The
conductive layer 5081 is provided over part of the conductive layer
5071. The conductive layer 5082 is provided over part of the
conductive layer 5072. The conductive layer 5083 is provided over
part of the conductive layer 5073. The interlayer film 509 is
provided over the insulating film 506, the conductive layers 5071
to 5073, and the conductive layers 5081 to 5083. The interlayer
film 510 is provided over the interlayer film 509. The electrodes
5111 to 5113 are provided over the interlayer film 510.
[0100] The transistor 321 includes the semiconductor layer 5031,
the insulating film 506, the conductive layer 5071, and the
conductive layer 5081. The semiconductor layer 5031 includes a pair
of impurity regions 5041, a pair of impurity regions 5051 which is
provided between the pair of impurity regions 5041 and has lower
impurity concentration than the impurity regions 5041. and a
channel region between the pair of impurity regions 5051. In the
transistor 321, the insulating film 506 functions as a gate
insulating film. The conductive layers 5071 and 5081 function as a
gate electrode. The pair of impurity regions 5041 functions as a
source region and a drain region. The pair of impurity regions 5051
functions as low concentration impurity regions (also referred to
as lightly doped drain (LDD) regions). The electrodes 5111 are
electrically connected to the impurity region 5041 through opening
portions provided in the insulating film 506 and the interlayer
films 509 and 510. At this time, the pair of electrodes 5111
functions as a source electrode and a drain electrode.
[0101] The capacitor 323 includes the semiconductor layer 5032, the
insulating film 506, the conductive layer 5072, and the conductive
layer 5082. The electrodes 5112 are electrically connected to the
semiconductor layer 5032 through opening portions provided in the
insulating film 506 and the interlayer films 509 and 510.
[0102] The transistor 331 includes the semiconductor layer 5033,
the insulating film 506, the conductive layer 5073, and the
conductive layer 5083. The semiconductor layer 5033 includes a pair
of impurity regions 5042, a pair of impurity regions 5052 which is
provided between the pair of impurity regions 5042 and has lower
impurity concentration than the impurity regions 5042, and a
channel region between the pair of impurity regions 5052. In the
transistor 331, the insulating film 506 functions as a gate
insulating film. The conductive layers 5073 and 5083 function as a
gate electrode. The pair of impurity regions 5042 functions as a
source region and a drain region. The pair of impurity regions 5052
functions as low concentration impurity regions. The electrodes
5113 are electrically connected to the impurity region 5042 through
opening portions provided in the insulating film 506 and the
interlayer films 509 and 510. At this time, the pair of electrodes
5113 functions as a source electrode and a drain electrode.
[0103] For the semiconductor layers 5031 to 5033, an amorphous
semiconductor, a microcrystalline (microcrystal) semiconductor, or
a polycrystalline semiconductor can be used, for example. Moreover,
an oxide semiconductor can be used. As the oxide semiconductor,
zinc oxide or an oxide semiconductor represented by
InMO.sub.3(ZnO).sub.m (m>0) can be used, for example. Note that
M represents one or more of metal elements selected from gallium
(Ga), iron (Fe), nickel (Ni), manganese (Mn), or cobalt (Co). As an
example, M may be Ga or may include the above metal element in
addition to Ga, for example, M may be Ga and Ni or Ga and Fe.
Moreover, the oxide semiconductor may contain a transition metal
element such as Fe or Ni or oxide of the transition metal element
as an impurity element in addition to the metal element contained
as M. Alternatively, a single crystal semiconductor can be used.
For example, single crystal silicon can be used in the case of
employing a structure where the substrate 501 and the semiconductor
layers 5031 to 5033 are attached to each other with a bonding layer
therebetween. At this time, the bonding layer has a smooth and
hydrophilic bonding surface and can be formed using silicon oxide
containing hydrogen, silicon nitride containing hydrogen, silicon
nitride containing oxygen and hydrogen, silicon oxynitride, silicon
nitride oxide, or the like.
[0104] As silicon oxide containing hydrogen, silicon oxide formed
by a chemical vapor deposition method using organosilane is
preferably used, for example. This is because the substrate 501 and
the semiconductor layers 5031 to 5033 can be firmly bonded to each
other with a silicon oxide film formed using organosilane, for
example. As organosilane, a silicon-containing compound such as
tetraethoxysilane (TEOS, Si(OC.sub.2H.sub.5).sub.4),
tetramethylsilane (TMS, Si(CH.sub.3).sub.4),
tetramethylcyclotetrasiloxane (TMCTS), octamethylcyclotetrasiloxane
(OMCTS), hexamethyldisilazane (HMDS), triethoxysilane
(SiH(OC.sub.2H.sub.5).sub.3), or tris(dimethylamino)silane
(SiH(N(CH.sub.3).sub.2).sub.3) can be used, for example.
[0105] Note that when the bonding layer is formed using silicon
oxide, the bonding layer can be formed by a CVD method using
monosilane, disilane, or trisilane as a source gas. Further, the
silicon oxide layer serving as the bonding layer may be a thermal
oxide film and preferably contains chlorine.
[0106] Silicon nitride containing hydrogen can be formed by a
plasma CVD method using a silane gas and an ammonia gas. Further,
hydrogen may be added to the gases. Silicon nitride containing
oxygen and hydrogen can be formed by a plasma CVD method using a
silane gas, an ammonia gas, and a nitrous oxide gas. In either
case, silicon oxide, silicon oxynitride, or silicon nitride oxide,
which contains hydrogen and is formed using a silane gas or the
like as a source gas by a CVD method such as a plasma CVD method, a
reduced pressure CVD method, or an atmosphere pressure CVD method,
can be used for the bonding layer.
[0107] As the insulating film 506, a silicon nitride film, a
silicon oxide film, or a silicon oxide film containing nitrogen can
be used, for example.
[0108] For the first conductive layers 5071, 5072, and 5073, an
element selected from titanium, tungsten, tantalum, molybdenum,
neodymium, cobalt, zirconium, zinc, ruthenium, rhodium, palladium,
osmium, iridium, platinum, aluminum, gold, silver, or copper; an
alloy material or a compound material containing the above element
as its main component; or nitride of the above element can be used,
for example.
[0109] For the second conductive layers 5081, 5082, and 5083, an
element selected from titanium, tungsten, tantalum, molybdenum,
neodymium, cobalt, zirconium, zinc, ruthenium, rhodium, palladium,
osmium, iridium, platinum, aluminum, gold, silver, or copper; an
alloy material or a compound material containing the above element
as its main component; or nitride of the above element can be used,
for example.
[0110] Note that in this embodiment, the transistors 321 and 331
are described as staggered transistors; however, this embodiment is
not limited thereto, and an inverted staggered transistor or a
coplanar transistor can be used. Moreover, a transistor with
another structure, such as a dual-gate transistor or a double-gate
transistor, can also be used.
[0111] As the interlayer films 509 and 510, a silicon oxide film, a
silicon nitride film, or a silicon oxide film containing nitrogen
can be used, for example. Further, the interlayer film 509 can also
function as a protective film.
[0112] For the electrodes 5111 to 5113, an element selected from
titanium, tungsten, tantalum, molybdenum, neodymium, cobalt,
zirconium, zinc, ruthenium, rhodium, palladium, osmium, iridium,
platinum, aluminum, gold, silver, or copper; an alloy material or a
compound material containing the above element as its main
component; or nitride of the above element can be used, for
example. Alternatively, the electrodes 5111 to 5113 can have a
layered structure using a plurality of materials.
[0113] The interlayer film 512 can be formed using any of the
materials which can be used for the interlayer films 509 and 510,
for example.
[0114] In the pixel illustrated in FIG. 5, a PIN photodiode is used
as the photodetector element 332. The structure of the
photodetector element 332 will be described below.
[0115] The photodetector element 332 in FIG. 5 includes an
electrode 5132, the electrode 5133, semiconductor layers 514, 515,
and 516, and the electrode 5202. Note that FIG. 5 illustrates that
the photodetector element 332 overlaps with only the transistor 331
in the plan view; however, this embodiment is not limited thereto,
and the photodetector element 332 can be placed so as to overlap
with the transistor 321 and the capacitor 323.
[0116] The electrodes 5132 and 5133 are provided over the
interlayer film 512, The semiconductor layer 514 is provided so as
to be in contact with the electrode 5132. The semiconductor layer
515 is provided over the semiconductor layer 514. The semiconductor
layer 516 is provided over the semiconductor layer 515. The
electrode 5202 is provided over the protective film 519.
[0117] The semiconductor layer 514 has one of p-type conductivity
and n-type conductivity. The semiconductor layer 515 has a higher
resistance than the semiconductor layer 514. The provision of the
semiconductor layer 515 can increase the thickness of a depletion
layer, so that adverse effects of parasitic capacitance can be
reduced. The semiconductor layer 516 has a lower resistance than
the semiconductor layer 515. For example, an intrinsic
semiconductor can be used for the semiconductor layer 515; however,
the semiconductor layer 515 is not necessarily limited to an
intrinsic semiconductor, and can have a structure where an impurity
element is added. The semiconductor layers 514, 515, and 516 can be
formed using amorphous silicon, microcrystalline silicon,
polycrystalline silicon, or single crystal silicon, for example. In
the photodetector element 332, the electrode 5132 functions as part
of the first terminal, and the semiconductor layers 514 to 516
function as a photoelectric conversion layer, Further, the
semiconductor layer 516, the electrode 5202, and the electrode 5133
are electrically connected to each other through opening portions
provided in the protective film 517, the color layer 518, and the
protective film 519. At this time, the electrodes 5202 and 5133
function as part of the second terminal.
[0118] The electrode 5131 is electrically connected to one of the
pair of electrodes 5111 through an opening portion provided in the
interlayer film 512. At this time, the electrode 5131 functions as
a wiring.
[0119] The color layer 518 is a layer in which a dye, a pigment, or
the like is used as a color material. Full color can be expressed
using three kinds of color layers of R, G, and B, for example. In
this embodiment, the color layer 518 is preferably provided so as
to overlap with part or all of the photodetector element 332 in the
plan view. When the color layer 518 is provided so as to overlap
with the photodetector element 332, light is likely to enter the
photodetector element 332 through the color layer 518. Further, in
the plan view, the photodetector element 332 and the color layer
518 are not necessarily provided so as to overlap with each other.
The photodetector element 332 and the color layer 518 can be placed
in a different way, for example, they are placed so as not to
overlap with each other in the plan view, as long as light enters
the photodetector element 332 through the color layer 518.
[0120] Although the protective films 517 and 519 are not
necessarily provided, the provision of the protective films 517 and
519 can prevent the pigment, the dye, or the like from diffusing
from the color layer 518. As the protective films 517 and 519,
silicon nitride films can be used, for example.
[0121] In the pixel in FIG. 5, a liquid crystal element of a
vertical electric field mode, which includes a liquid crystal layer
between a pair of electrodes, is used as the liquid crystal element
322. The structure of the liquid crystal element 322 will be
described below. Note that the operation mode of the image
input-output device in this embodiment is not limited to a vertical
electric field mode, and a transverse electric field mode can be
used, for example.
[0122] The liquid crystal element 322 illustrated in FIG. 5
includes an electrode 5201, partition layers 521, a liquid crystal
layer 522, and an electrode 523.
[0123] The electrode 5201 is provided over the protective film 519.
The partition layers 521 are selectively provided over at least the
electrode 5201. The liquid crystal layer 522 is provided over at
least the electrode 5201. The electrode 523 is provided over the
partition layers 521 and the liquid crystal layer 522. The
substrate 524 is provided over the electrode 523.
[0124] Further, the electrode 5201 is electrically connected to the
electrode 5131 through an opening portion provided in the
protective film 517, the color layer 518, and the protective film
519. At this time, the electrode 5201 functions as a pixel
electrode and the electrode 523 functions as a counter
electrode.
[0125] For the electrodes 5201, 5202, and 523, any of the materials
which can be used for the electrodes 5111 to 5113 can be used.
[0126] Note that the liquid crystal element 322 can be provided
with an alignment film.
[0127] Note that in FIG. 5, the electrode 5201 overlaps with part
or all of the transistor 321 and the capacitor 323 in the plan
view; however, this embodiment is not limited thereto. and for
example, the electrode 5201 can be provided so as to overlap with
the transistor 321, the capacitor 323, the transistor 331, and the
photodetector element 332. Alternatively, the electrode 5201 can be
placed so as not to overlap with any of the transistor 321, the
capacitor 323, the transistor 331, and the photodetector element
332. Further, when the electrode 5201 is provided over the
photodetector element 332, the use of a normally white liquid
crystal element can increase the transmittance of the liquid
crystal layer 522 even in the read period; thus, light efficiently
enters the photodetector element 332.
[0128] As illustrated in FIG. 5, the image input-output device in
this embodiment has a structure where a transistor, a photodetector
element, and a color layer are provided over one substrate. The
above structure is referred to as a color filter on array (COA)
structure in this specification. With the COA structure, the
distance between the photodetector element and the color layer can
be made shorter than the in the case in which a substrate where a
color layer is formed is different from a substrate where a
photodetector element and a display element are formed.
Accordingly, light can be prevented from entering, for example, a
photodetector element on which light passing through a color layer
of a predetermined color is to enter, through a color filter of a
color other than the predetermined color, and the reading accuracy
can be improved. Moreover, the COA structure can improve the
alignment accuracy as compared to the case where a color layer and
an element such as a transistor are provided over different
substrates; thus, the aperture ratio can be increased.
[0129] Further, in the image input-output device in this
embodiment, the color layer functions as a planarization film.
Accordingly, it is not necessary to provide an additional
planarization film, and the process can be simplified.
[0130] Furthermore, the image input-output device in this
embodiment has a multilayer wiring structure. Although it is not
necessary to employ a multilayer wiring structure, the multilayer
wiring structure can reduce the circuit area.
[0131] In addition, a photodetector element with another structure
can be used in the image input-output device in this embodiment. A
structure of a pixel in an image input-output device including a
photodetector element with another structure is described with
reference to FIG. 6. FIG. 6 is a cross-sectional view illustrating
an example of a structure of a pixel in the image input-output
device in this embodiment. Note that in the structure of the image
input-output device illustrated in FIG. 6, the description of the
pixel in the image input-output device in FIG. 5 is employed as
appropriate for the same portions as the image input-output device
in FIG. 5.
[0132] The pixel structure illustrated in FIG. 6 is as follows. The
pixel includes the photodetector element 332 including a
semiconductor layer 5034 and a pair of electrodes 5114. The
semiconductor layer 5034 includes an impurity region 5043 having
one of p-type conductivity and n-type conductivity, and an impurity
region 5044 having the other of p-type conductivity and n-type
conductivity. One of the pair of electrodes 5114 is electrically
connected to the impurity region 5043 through an opening portion
provided in the insulating film 506 and the interlayer films 509
and 510. The other of the pair of electrodes 5114 is electrically
connected to the impurity region 5044 through an opening portion
provided in the insulating film 506 and the interlayer films 509
and 510.
[0133] As described above, the photodetector element 332
illustrated in FIG. 6 is a lateral-junction PIN diode in which one
semiconductor layer includes a region of p-type conductivity and a
region of n-type conductivity. By using the lateral-junction PIN
diode, the thickness of the image input-output device can be
reduced. Moreover, the PIN diode can be formed together with the
transistors 321 and 331, so that the number of steps can be
reduced.
[0134] In addition, the image input-output device in this
embodiment can include a light blocking layer (also referred to as
a black matrix). A structure of the image input-output device
including a light blocking layer will be described with reference
to FIG. 7. FIG. 7 is a cross-sectional view illustrating an example
of a structure of the image input-output device in the case where a
light blocking layer is provided. Note that in the structure of the
image input-output device illustrated in FIG. 7, the description of
the pixel in the image input-output device in FIG. 5 is employed as
appropriate for the same portions as the image input-output device
in FIG. 5.
[0135] The image input-output device illustrated in FIG. 7 includes
a light blocking layer 5251 which is selectively provided over the
protective film 517, in addition to the structure of the image
input-output device in FIG. 5.
[0136] In the image input-output device in FIG. 7, the light
blocking layer 5251 is provided on the substrate 501 side. By
providing the light blocking layer 5251 on the substrate 501 side,
the alignment accuracy can be improved. Note that the light
blocking layer 5251 is not necessarily provided on the substrate
501 side, and can be provided on the substrate 524 side.
[0137] As illustrated in FIG. 7, with the structure where the light
blocking layer 5251 is provided, for example, light can be
prevented from entering the transistor; thus, deterioration of the
transistor can be prevented.
[0138] The image input-output device in this embodiment can have a
variety of functions by utilizing the above-described display
function and read function. As an example, a function of inputting
and outputting text, a function of detecting position, and a
function of inputting and outputting documents are described with
reference to FIGS. 8A and 8B and FIG. 9, FIGS. 8A and 8B and FIG. 9
each illustrate an example of a function of the image input-output
device in this embodiment.
[0139] FIG. 8A illustrates a function of inputting and outputting
text. As illustrated in FIG. 8A, an input means 601 is moved over a
pixel portion 600 so that letters are written, for example.
Accordingly, read operation is performed in the pixel portion 600,
so that the trace of the input means 601 is read as data, and in
the next display operation, the trace of the input means 601 is
displayed on the pixel portion 600. Through the above operation,
the operation of inputting and outputting text can be performed.
Note that since the image input-output device, which is one
embodiment of the invention disclosed in this specification,
performs the read operation using the illuminance of light entering
the photodetector circuit, the input means 601 is not necessarily
in contact with the pixel portion 600. When text is input with the
input means 601 in contact with the pixel portion 600, letters can
be input to the pixel portion 600 as if letters are actually
written on paper, for example; accordingly, letters can be input
without discomfort. Further. by using the input means 601 including
a light source, the operation of inputting and outputting text can
be performed by detecting the illuminance of incident light from
the light source in the input means.
[0140] FIG. 8B illustrates a function of detecting position. As
illustrated in FIG. 8B, when the input means 601 is placed at a
given position 602 on the pixel portion 600, the read operation is
performed, so that information on where the positions 602 is
located can be obtained. Through the above operation, the operation
of detecting position can be performed. For example, the case is
considered in which the image input-output device is designed so
that a predetermined program is executed when there is an input to
a predetermined position. in this case, when it is determined that
there is an input to the given position 602, a program
corresponding to the position 602 can be executed by using the
position detection function. Note that FIG. 8B illustrates a finger
as the input means 601, and a fingerprint can be read by using the
finger. For example, when fingerprint data is stored in a memory
circuit and the read fingerprint is compared with the fingerprint
data, fingerprint identification can be performed. Moreover, the
input means 601 is not limited to the finger of the hand, and a pen
or the like can be used as the input means 601, for example.
[0141] FIG. 9 illustrates a function of inputting and outputting
documents. As illustrated in FIG. 9, when a document 603 is placed
on the pixel portion 600 so that a surface to be read faces the
pixel portion 600, the read operation is performed in each
photodetector circuit. Accordingly, the document 603 can be read as
data, and in the next display operation, the read document can be
displayed on the pixel portion 600. Note that since the image
input-output device, which is one embodiment of the invention
disclosed in this specification, performs the read operation using
the illuminance of incident light, the document 603 does not
necessarily touch the pixel portion 600 in FIG. 9. Further, in the
image input-output device, which is one embodiment of the invention
disclosed in this specification, when a color layer is provided in
the photodetector circuit, a document can be read in full color and
displayed in full color.
[0142] Note that the image input-output device in this embodiment
can have another function without limitation to the above
functions, as long as the function can be realized using the
display operation or the read operation.
[0143] Note that this embodiment can be implemented in combination
with other embodiments as appropriate.
Embodiment 3
[0144] In this embodiment, a method for manufacturing an image
input-output device, which is one embodiment of the invention
disclosed in this specification, will be described.
[0145] A method for manufacturing an image input-output device in
this embodiment will be described with reference to FIGS. 10A to
10C, FIGS. 11A to 11C, FIGS. 12A and 12B, FIGS. 13A and 138, FIGS.
14A and 14B, FIGS. 15A and 15B, and FIG. 16. FIGS. 10A to 10C,
FIGS. 11A to 11C, FIGS. 12A and 12B, FIGS. 13A and 13B, FIGS. 14A
and 14B, FIGS. 15A and 158, and FIG. 16 are cross-sectional views
illustrating a method for manufacturing a pixel of the image
input-output device in this embodiment. Note that in this
embodiment, a method for manufacturing the image input-output
device illustrated in FIG. 5 is described as an example.
[0146] First, as illustrated in FIG. 10A, the base film 502 is
formed over the substrate 501, and the semiconductor layers 5031,
5032, and 5033 are formed as island-shaped semiconductor layers
over the base film 502. The base film 502 can be formed by a plasma
CVD method, for example. The semiconductor layers 5031 to 5033 can
be formed by a photolithography method, for example.
[0147] Then, as illustrated in FIG. 10B, the insulating film 506 is
formed over the semiconductor layers 5031 to 5033. The insulating
film 506 can be formed by a plasma CVD method, for example.
[0148] Next, as illustrated in FIG, 10C, a gate electrode or an
electrode of a capacitor is formed over the insulating film 506
provided over the semiconductor layer. Specifically, the first
conductive layer 5071 is formed over the insulating film 506
provided over the semiconductor layer 5031, and the second
conductive layer 5081 is formed over part of the first conductive
layer 5071. The first conductive layer 5072 is formed over the
insulating film 506 provided over the semiconductor layer 5032, and
the second conductive layer 5082 is formed over part of the first
conductive layer 5072. The first conductive layer 5073 is formed
over the insulating film 506 provided over the semiconductor layer
5033, and the second conductive layer 5083 is formed over part of
the first conductive layer 5073. The first and second conductive
layers 5071 and 5081, the first and second conductive layers 5072
and 5082, and the first and second conductive layers 5073 and 5083
can be formed by a sputtering method, for example.
[0149] Then, as illustrated in FIG. 11A, by addition of an impurity
element, the pair of first impurity regions 5041 and the pair of
second impurity regions 5051 are formed in the semiconductor layer
5031, and the pair of first impurity regions 5042 and the pair of
second impurity regions 5052 are formed in the semiconductor layer
5033. As the impurity element, phosphorus can be used for imparting
n-type conductivity and boron for imparting p-type conductivity,
for example.
[0150] Next, as illustrated in FIG. 11B, the interlayer film 509 is
formed over the first and second conductive layers 5071 and 5081,
the first and second conductive layers 5072 and 5082, the first and
second conductive layers 5073 and 5083, and the insulating film
506. The interlayer film 510 is formed over the interlayer film
509.
[0151] Next, opening portions are provided in the interlayer films
509 and 510. Then, as illustrated in FIG. 11C, the electrodes 5111
are formed so as to be in contact with the first impurity region
5041 through the opening portions; the electrodes 5112 are formed
so as to be in contact with the semiconductor layer 5032 through
the opening portions; and the electrodes 5113 are formed so as to
be in contact with the first impurity region 5042 through the
opening portions.
[0152] Then, as illustrated in FIG. 12A, the interlayer film 512 is
formed over the electrodes 5111 to 5113 and the interlayer film
510.
[0153] Next, as illustrated in FIG. 12B, an opening portion is
provided in the interlayer film 512, and the electrode 5131 is
formed so as to be electrically connected to one of the pair of
electrodes 5111 through the opening portion. Further, the
electrodes 5132 and 5133 are formed over the interlayer film
512.
[0154] Then, as illustrated in FIG. 13A, the semiconductor layer
514 is formed so as to be in contact with the electrode 5132, the
semiconductor layer 515 is formed over the semiconductor layer 514,
and the semiconductor layer 516 is formed over the semiconductor
layer 515.
[0155] Next, as illustrated in FIG. 13B, the protective film 517 is
formed over the interlayer film 512, the electrodes 5131 to 5133,
and the semiconductor layers 514 to 516.
[0156] Then, as illustrated in FIG. 14A, the color layer 518 is
formed over the protective film 517. The color layer 518 can be
formed by a photolithography method, a printing method, or an
inkjet method in the case of using a dye, and can be formed, for
example, by a photolithography method, a printing method, an
electrodeposition method, an electrophotographic method, or the
like in the case of using a pigment. Here, the color layer is
formed by an inkjet method, By using an inkjet method, the color
layer can be formed at room temperature, can be formed at a low
vacuum, or can be formed using a large substrate. Since the color
layer can be formed without using a mask (reticle), costs and the
number of steps can be reduced. Moreover, since a film is formed
only where needed, a material is not wasted and costs can be
reduced as compared to a manufacturing method in which etching is
performed after a film is formed over the entire surface. Then,
opening portions are provided in part of the color layer 518.
[0157] Next, as illustrated in FIG. 14B, the protective film 519 is
formed over the color layer 518 and surfaces of the protective film
517, which are exposed by the opening portions in the color layer
518.
[0158] Then, as illustrated in FIG. 15A, the protective films 517
and 519 in the opening portions are removed by etching.
[0159] Next, as illustrated in FIG. 15B, the electrode 5201 is
formed so as to be in contact with the electrode 5131 through an
opening portion provided in the protective film 517, the color
layer 518, and the protective film 519. Moreover, the electrode
5202 is formed so as to be in contact with the semiconductor layer
516 and the electrode 5133 through opening portions provided in the
protective film 517, the color layer 518, and the protective film
519.
[0160] Then, as illustrated in FIG. 16, the partition layers 521
and the liquid crystal layer 522 are selectively formed over the
electrodes 5201 and 5202, and the substrate 524 provided with the
electrode 523 in advance is attached to the substrate 501.
[0161] Through the above steps, the image input-output device with
the pixel structure illustrated in FIG. 5 can be formed. Note that
a display circuit and a reading circuit can be formed over the same
one substrate by the manufacturing method in this embodiment.
[0162] Note that this embodiment can be implemented in combination
with other embodiments as appropriate.
Embodiment 4
[0163] In this embodiment, a method for manufacturing an image
input-output device including a light blocking layer, which is one
embodiment of the invention disclosed in this specification, will
be described.
[0164] As has been illustrated in FIG. 7, a light blocking layer
can be provided together with a color layer in one embodiment of
the invention disclosed in this specification. A method for
manufacturing an image input-output device including a light
blocking layer will be described with reference to FIGS. 17A to
17C. FIGS. 17A to 17C are cross-sectional views illustrating an
example of a method for manufacturing a color layer and a light
blocking layer in this embodiment.
[0165] First, as illustrated in FIG. 17A, an element formation
layer 802 is formed over a substrate 801. The element formation
layer 802 corresponds to the element formation layer 503 in FIG. 5.
Then, a protective film 803 is formed over the element formation
layer 802. The protective film 803 corresponds to the protective
film 517 in FIG. 5. Further, a light blocking film 804 is formed
over the protective film 803.
[0166] Next, as illustrated in FIG. 17B, resist masks 8051 to 8054
are selectively formed over the light blocking film 804, and the
light blocking film 804 is etched using the resist masks 8051 to
8054 as masks to form light blocking layers 8041 to 8044.
[0167] Then, as illustrated in FIG. 17C, color layers 8061 to 8063
are formed between the light blocking layers 8041 to 8044. The
color layers 8061 to 8063 can be formed by an inkjet method, a
photolithography method, or an electrodeposition method, for
example. Further, the color layers 8061 to 8063 can be the same in
color or can have different colors such as R, G, and B.
[0168] Through the above steps, the light blocking layer and the
color layer can be formed. In the case of providing a light
blocking layer and a color layer, the light blocking layers are
formed first and the color layer is formed between the light
blocking layers using the light blocking layers as partition layers
as shown in this embodiment, whereby the color layer can be more
easily formed.
[0169] Note that this embodiment can be implemented in combination
with other embodiments as appropriate.
Embodiment 5
[0170] In this embodiment, an image input-output device including a
driver circuit will be described as one embodiment of the invention
disclosed in this specification.
[0171] A structure of an image input-output device in this
embodiment will be described with reference to FIG. 18. FIG. 18 is
a block diagram illustrating an example of a structure of the image
input-output device in this embodiment.
[0172] The image input-output device illustrated in FIG. 18
includes a pixel portion 901, a first driver circuit 902, and a
second driver circuit 903.
[0173] The pixel portion 901 has a dot matrix structure including a
plurality of pixels 904 arranged in the row and column directions.
As the structure of the pixel 904, the structure of the pixel shown
in the above embodiments can be used, for example.
[0174] The first driver circuit 902 is a circuit mainly for
selecting a pixel where display and reading are performed, and
includes a scan line driver circuit 905 and a potential control
line driver circuit 906. Note that a plurality of first driver
circuits 902 can be provided, for example, without limitation to
the structure illustrated in FIG. 18.
[0175] The second driver circuit 903 has a function of outputting a
data signal for display to the pixel 904 selected by the first
driver circuit 902, and a function of storing image data read in
the pixel 904.
[0176] Next, operation of the image input-output device in FIG. 18
will be described.
[0177] As has been described in the above embodiments, the
operation of the image input-output device in FIG. 18 is classified
into two periods of a display period and a read period. The
operation in each period will be described below.
[0178] First, in the display period, the pixel 904 to which data is
written is selected by the scan line driver circuit 905 in the
first driver circuit 902, and a data signal is output from the
second driver circuit 903 to the selected pixel 904, so that the
selected pixel 904 enters into a display state. Further, the pixels
904 are selected per row by the first driver circuit 902, and data
is written into all the pixels 904.
[0179] Next, in the read period, the pixel 904 where the
illuminance of incident light is read is selected by the potential
control line driver circuit 906 in the first driver circuit 902. In
response to a signal input from the potential control line driver
circuit 906, the selected pixel 904 outputs a data signal to the
second driver circuit 903 in accordance with a current generated
corresponding to the illuminance of incident light, whereby data of
the illuminance of incident light is read. Further, the pixels 904
are selected per row by the second driver circuit 903, and
illuminance data is read in all the pixels 904.
[0180] The display operation and the read operation are performed
in the pixel portion as described above, so that an image
input-output device can have a variety of functions such as a
function of detecting position, a function of inputting and
outputting text, and a function of inputting and outputting
documents, which are described in the above embodiment.
[0181] Note that this embodiment can be implemented in combination
with other embodiments as appropriate.
Embodiment 6
[0182] In this embodiment, an electronic device including the image
input-output device, which is one embodiment of the invention
disclosed in this specification, in a display portion will be
described.
[0183] By applying the image input-output device, which is one
embodiment of the invention disclosed in this specification, to a
display portion of a variety of electronic devices, an electronic
device having a variety of functions in addition to a display
function can be provided. Specific examples of electronic devices
to which the image input-output device, which is one embodiment of
the invention disclosed in this specification, is applied will be
described with reference to FIGS. 19A to 19F, FIGS. 19A to 19F each
illustrate an example of a structure of an electronic device in
this embodiment.
[0184] FIG. 19A illustrates a personal digital assistant, The
personal digital assistant illustrated in FIG. 19A includes at
least a display portion 1001. The image input-output device, which
is one embodiment of the invention disclosed in this specification,
can be placed in the display portion 1001. When the image
input-output device, which is one embodiment of the invention
disclosed in this specification, is placed in the display portion
1001, the personal digital assistant can be used in place of a
variety of portable devices. For example, when the display portion
1001 is provided with an operation portion 1002 by using a position
detection function, the personal digital assistant can be used as a
mobile phone. Note that the operation portion 1002 is not
necessarily provided in the display portion 1001, and additional
operation buttons may be provided. Moreover, the personal digital
assistant can be used as a notepad by using a text input-output
function or used as a handy scanner by using a document
input-output function.
[0185] FIG. 19B illustrates an information guide terminal including
an automotive navigation system, for example. The information
terminal illustrated in FIG. 19B includes at least a display
portion 1101, and can also include operation buttons 1102, an
external input terminal 1103, and the like, The image input-output
device, which is one embodiment of the invention disclosed in this
specification, can be provided in the display portion 1101. When
the image input-output device, which is one embodiment of the
invention disclosed in this specification, is placed in the display
portion 1101, the information guide terminal can be operated
without touching a pixel portion, and thus can be operated more
easily.
[0186] FIG. 19C illustrates a laptop personal computer. The laptop
personal computer illustrated in FIG. 19C includes a housing 1201,
a display portion 1202, a speaker 1203, an LED lamp 1204, a
pointing device 1205, a connection terminal 1206, and a keyboard
1207, The image input-output device, which is one embodiment of the
invention disclosed in this specification, can be provided in the
display portion 1202. When the image input-output device, which is
one embodiment of the invention disclosed in this specification, is
placed in the display portion 1202, input operation can be
performed using a text input-output function by directly writing
letters on the display portion 1202. Further, the keyboard 1207 can
be provided in the display portion 1202.
[0187] FIG. 19D illustrates a portable game machine. The portable
game machine illustrated in FIG. 19D includes a first display
portion 1301, a second display portion 1302, a speaker 1303, a
connection terminal 1304, an LED lamp 1305, a microphone 1306, a
recording medium reading portion 1307, operation buttons 1308, and
a sensor 1309. The image input-output device, which is one
embodiment of the invention disclosed in this specification, can be
provided in one or both of the first display portion 1301 and the
second display portion 1302. When the image input-output device,
which is one embodiment of the invention disclosed in this
specification, is placed in one or both of the first display
portion 1301 and the second display portion 1302, the portable game
machine can be operated without touching a pixel portion, and thus
can be operated more easily with an input means (e.g., a finger or
a pen).
[0188] FIG. 19E illustrates a stationary information terminal. The
stationary information terminal illustrated in FIG. 19E includes at
least a display portion 1401. Note that the display portion 1401
can also be provided in a plane portion 1402. Moreover, additional
operation buttons or the like can be provided for the plane portion
1402. The image input-output device, which is one embodiment of the
invention disclosed in this specification, can be provided in the
display portion 1401. When the image input-output device, which is
one embodiment of the invention disclosed in this specification, is
placed in the display portion 1401, the stationary information
terminal can have a variety of functions and for example, can be
used as an automated teller machine or an information terminal
(also referred to as a multimedia station) for ordering information
goods such as a ticket.
[0189] FIG. 19F illustrates a display. The display illustrated in
FIG. 19F includes a housing 1501, a display portion 1502, a speaker
1503, an LED lamp 1504, operation buttons 1505, a connection
terminal 1506, a sensor 1507, a microphone 1508, and a support base
1509. The image input-output device, which is one embodiment of the
invention disclosed in this specification, can be provided in the
display portion 1502. When the image input-output device, which is
one embodiment of the invention disclosed in this specification, is
placed in the display portion 1502, the display portion can have a
variety of functions by combining a text input-output function, a
position detection function, and a document input-output
function.
[0190] As described above, by providing the image input-output
device, which is one embodiment of the invention disclosed in this
specification, in a display portion of an electronic device, a
multifunctional electronic device can be provided.
[0191] Note that this embodiment can be implemented in combination
with other embodiments as appropriate.
[0192] This application is based on Japanese Patent Application
serial no. 2008-286043 filed with Japan Patent Office on Nov. 7,
2008, the entire contents of which are hereby incorporated by
reference.
* * * * *